Answer:
1 yoghurt = $0.48 and 1 grapefruit = $0.27
Step-by-step explanation:
let y be the cost of one yoghurt and g the cost of one grapefruit, then
set up a pair of simultaneous equations and solve for y and g
3y + 5g = 2.79 → (1)
4y + 7g = 3.81 → (2)
multiplying (1) by 4 and (2) by - 3 and adding the result will eliminate y
12y + 20g = 11.16 → (3)
- 12y - 21g = - 11.43 → (4)
add (3) and (4) term by term to eliminate y
(12y - 12y) + (20g - 21g) = 11.16 - 11.43
0 - g = - 0.27
- g = - 0.27 ( multiply both sides by - 1
g = 0.27
substitute g = 0.27 into either of the 2 original equations and solve for y
substituting into (1)
3y + 5(0.27) = 2.79
3y + 1.35 = 2.79 ( subtract 1.35 from both sides )
3y = 1.44 ( divide both sides by 3 )
y = 0.48
The cost of 1 yoghurt is $0.48 and the cost of 1 grapefruit is $0.27
