In one week a music store sold 9 guitars for a total of 3611

In one week, a music store sold 9 guitars for a total of $3611. Electric guitars sold for $479 each and acoustic guitars sold for $339 each. How many of each type of guitar were sold?

Solution

Let electric guitars sold be x
elec guitars------------- acous guitars-------------- total
x-------------------------- 9-x------------------------9
479-------------------------339-----------------------3611

479*x+(9-x)*339=3611
479x + 3051- 339x=3611
140x= 3611-3051
140x=560
x=4 ------------ Electric gutars
9-4 = 5 Number of Acoustic guitars