Answer:
$6.40
Step-by-step explanation:
let d be the cost of 1 doughnut and b the cost of 1 burger.
set up 2 equations and solve for b
9b + d = 31.3 → (1)
6b + 3d = 26.7 → (2)
multiplying (1) by - 3 and adding to (2) will eliminate d
- 27b - 3d = - 93.9 → (3)
add (2) and (3) term by term to eliminate d
- 21b + 0 = - 67.2
- 21b = - 67.2 ( divide both sides by - 21 )
b = 3.2
then
cost of 2 burgers = 2 × $3.20 = $6.40
