Two apples balance three pears. One apple weighs 90 grams. How many grams does one pear weigh?
Hints
Take them one at a time. The first gives nothing away.
1A nudge
Work out what one side weighs first.
2The strategy
Both sides of a balance weigh the same. Find the total on the apple side, then share it equally between the pears on the other side.
3The full solution
Two apples weigh 2 x 90 = 180 g, so three pears weigh 180 g and one pear weighs 180 divided by 3 = 60 g.
Solution— no shortcut on this one
The two sides weigh the same, so start with the side you know: two apples weigh 2 x 90 = 180 grams. That is also the weight of three pears, so one pear is 180 divided by 3 = 60 grams. Check: three 60-gram pears weigh 180, and so do two 90-gram apples. The transferable idea: compute one whole side of the balance before splitting the other.
Why this is on the test: Balance puzzles are ratios in disguise, and jumping straight to a per-item comparison skips the step that makes them easy.