3. The total value of the coins = 52. This is the answer because you can count 5 dimes and 2 pennies. A dime is worth 10 cents, so 10 x 5 = 50. A penney is worth one cent. 1 x 2 = 2. 50 + 2 = 52
15²-9²= x² use Pythagoras' theorum and square the two smaller sides to get the square of the hypotenuse (the diagonal) then rearrange this to get the above calculation