Question

four times daphne's age plus five times isaac's age adds up to 57. also, isaac's age is 11 less than twice daphne's age. how old is isaac?

Answer 1

4d + 5i = 57
i = 2d - 11

4d + 5(2d - 11) = 57
4d + 10d - 55 = 57
14d = 57 + 55
14d = 112
d = 112/14
d = 8 <== Daphne's age

i = 2d - 11
i = 2(8) - 11
i = 16 - 11
i = 5 <==Isaac's age