a purse contains 26 coins, some of which are dimes and the rest are nickels. Altogether, the coins are worth more than $2.10. At least how many dimes are in the purse?

3 answers

Let x = # dimes and y = # of nickels.

x + y = 26
y = 26-x

10x + 5y = 210

Substitute 26-x for y in second equation and solve for x. Insert that value into the first equation and solve for y. Check by inserting both values into the second equation.

at least 17

at least 16