💡 The Core Skill — Testing Answer Choices
The GED gives you a formula and asks which set of values satisfies it. Your strategy: plug each answer choice into the equation and see which one makes it true. You don't need to solve algebraically — just test each option. The one that gives g = 3 is the answer!
If you drive 60 miles in a car that gets 30 miles per gallon, you use:
g = d ÷ f = 60 ÷ 30 = 2 gallons ✅
The formula simply says: gallons used = miles driven ÷ miles per gallon.
miles ÷ (miles per gallon) = miles × (gallon/mile) = gallons ✅
The units cancel perfectly — this is how you know the formula is set up correctly.
When the GED asks "which combination satisfies the equation?", plug each answer into the formula:
d ÷ f = ? If the result equals the target value (3), that's the answer!
Test every choice if needed — this is faster than solving algebraically.
The problem says "uses 3 gallons" → we need d/f = 3.
"57 miles and 19 miles per gallon" → d = 57, f = 19
57 ÷ 19 = 3 → equals the target! ✅
Move on until you find the one that gives exactly 3.
| Choice | d (miles) | f (mpg) | d ÷ f | = 3? |
|---|---|---|---|---|
| A | 7 | 21 | 7 ÷ 21 = 0.33 | ❌ No |
| B ✅ | 57 | 19 | 57 ÷ 19 = 3 | ✅ YES! |
| C | 23 | 20 | 23 ÷ 20 = 1.15 | ❌ No |
| D | 32 | 35 | 32 ÷ 35 = 0.91 | ❌ No |
A common mistake is thinking "7 × 21 = 147" and not dividing. Or seeing 21 ÷ 7 = 3 and picking A. But the formula is d ÷ f (distance divided by fuel efficiency), not f ÷ d! Always check the order: numerator is d, denominator is f.
d=57, f=19 → g=3 ✅ (the correct answer)
d=7, f=21 → g=0.33 ❌ (Choice A — wrong order)
d=21, f=7 → g=3 ✅ (but this isn't one of the choices!)
d=60, f=20 → g=3 ✅ (another valid combination!)
d=90, f=30 → g=3 ✅ (any d = 3f works!)
A) p=$4, q=5 B) p=$6, q=4 C) p=$8, q=2
The GED always defines every variable (d = distance in miles, f = fuel efficiency in mpg). Read these before calculating anything!
"Uses 3 gallons" → target is g = 3. You're looking for which choice produces exactly this number.
The formula is d/f = g, NOT d × f. 57 ÷ 19 = 3, but 57 × 19 = 1,083. Wrong operation = wrong answer!
Choice A gives 7/21 = 0.33, but 21/7 = 3. The GED puts the numbers in the wrong order as a trap. Always compute d ÷ f, never f ÷ d!
If d is small and f is large (like 7 ÷ 21), you'll get less than 1 — clearly not 3. If d is about 3× larger than f (57 ≈ 3 × 19), it's likely the answer!
| Choice | Calculation | Result |
|---|---|---|
| 7 mi, 21 mpg | 7 ÷ 21 | 0.33 ❌ |
| 57 mi, 19 mpg ✅ | 57 ÷ 19 | 3 ✅ |
| 23 mi, 20 mpg | 23 ÷ 20 | 1.15 ❌ |
| 32 mi, 35 mpg | 32 ÷ 35 | 0.91 ❌ |