Each shape stands for a whole number. A triangle plus a triangle plus a triangle is 12, and a triangle plus a square is 9. What is the square?
Hints
Take them one at a time. The first gives nothing away.
1A nudge
The first line tells you one shape completely.
2The strategy
Three of the same shape adding to 12 pins that shape down exactly. Once you know it, the second line has only one unknown left.
3The full solution
Three triangles make 12, so a triangle is 4. Then 4 plus the square is 9, so the square is 5.
Solution— no shortcut on this one
Three triangles add to 12, so one triangle is 12 divided by 3 = 4. Substituting into the second line, 4 plus the square is 9, so the square is 9 - 4 = 5. Check: 4 + 5 = 9. The transferable idea: start with the line that has only one unknown, then carry what you learn into the next one.
Why this is on the test: Shape puzzles are simultaneous equations before a student has met the words, and answering with the wrong shape is the most common way to lose the mark.