solving a value mixture problem using a linear eqaution

Question

Melissa's Coffee Shop makes a blend that is a mixture of two types of coffee. Type A coffee costs Melissa $5.90

 per pound, and type B coffee costs $4.75

 per pound. This month's blend used twice as many pounds of type B coffee as type A, for a total cost of $569.80

. How many pounds of type A coffee were used

Answer 1

5.9a + 4.75(2a) = 569.8

5.9a + 9.5a = 569.8

15.4a = 569.8

a = 37 lbs