Question

Jimmy collects nickels and dimes. Right now, he has a total of 40 coins in his piggy bank. If there are seven times as many dimes as there are nickels, how many nickels does Jimmy have?

Answer 1

Number of nickels plus number of dimes equals total number of coins
so
n + d = 40

then they tell us that "there are seven times as many dimes as there are nickels"
this translates to
d = 7n

we then plug that into our first equation
and get
n + 7n = 40

then we solve for n
add like terms
8n = 40

then divide both sides by 8
n = 40/8 = 5

therefore Jimmy has 5 nickels