Q: A library has 7 rectangular tables and the remaining tables will be square tables. A rectangular table seats 10 pupils while a square table seats 4 pupils. How many square tables are needed so that 90 pupils can read at the same time?
A: The rectangular tables seat 7 * 10 = 70 pupils. The square tables will seat 90 - 70 = 20 pupils. The library needs 20 / 4 = 5 square tables. The answer is 5.

Q: Dawn, Lydia, and Donna have a total of 200 bananas. Dawn has 40 more bananas than Lydia. If Lydia has 60 bananas, how many bananas does Donna have?
A: If Lydia has 60 bananas, and Dawn has 40 more, then Dawn has 60 + 40 = 100 bananas. The total number of bananas Dawn and Lydia have is 100 + 60 = 160 bananas. Donna has 200 - 160 = 40 bananas. The answer is 40.

Q: Antonella has ten Canadian coins in her purse that are either loonies or toonies. A loonie equals $1 and a toonie equals $2. If she bought a $3 Frappuccino and still has $11, how many toonies did she initially have?
A:
If Antonella spent $3 and now has $11, that means initially she had $3 + $11 = $14. Let the number of loonies Antonella had be L and the number of toonies be T. Initially she had in her purse a total of 1L + 2T = $14. We also know that she had 10 coins in total or 10 = L + T. That means initially she had T = 10 - L toonies. Combining both equations we know that 14 = 1L + 2 * (10 - L). If we multiply through the parentheses, we get 14 = 1L + 20 - 2L. If we combine the variables on one side and the constants on another, we get - 6 = - 1L or L = 6. Knowing the value of L, we can solve for T = 10 - L = 10 - 6 = 4. The answer is 4.