Question 782536
Suppose that Maria has 130 coins consisting of pennies, nickels, and dimes. The number of nickels she has is 9 less than twice the number of pennies; the number of dimes she has is 23 less than three times the number of pennies. How many coins of each kind does she have? 

Pennies = x numbers

Nickels = 2x-9

Dimes = 3x-23


Add them up

x+2x-9+3x-23=130

6x-32=130
6x=130+32

6x=162
/6
x=27 ----------- pennies

substitute x to get the number of nickels and dimes