Answer:
An apple costs £0.25
A banana costs £0.34
Step-by-step explanation:
Let a be apples and b be bananas.
10a+5b=4.2
8a+10b=5.4
Solve for a:
10a+5b=4.2
Subtract 5b from both sides
10a=4.2-5b
Subtract 4.2 from both sides
10a-4.2= -5b
Multiply both sides by -1
-10a+4.2=5b
8a+10b=5.4
Subtract 10b from both sides
8a=5.4-10b
Subtract 5.4 from both sides
8a-5.4= -10b
Multiply both sides by -1
-8a+5.4= 10b
Divide both sides by 2
-4a+2.7=5b
Combine equations:
-4a+2.7= -10a+4.2
Add 10a to both sides
6a+2.7=4.2
Subtract 2.7 from both sides
6a=1.5
Divide both sides by 6
a=0.25
An apple costs £0.25
Solve for b:
10a+5b=4.2
Subtract 10a from both sides
5b= -10a+4.2
Subtract 4.2 from both sides
5b-4.2= -10a
Multiply both sides by -1
-5b+4.2=10a
8a+10b=5.4
Subtract 8a from both sides
10b= -8a+5.4
Subtract 5.4 from both sides
10b-5.4= -8a
Divide both sides by 4
2.5b-1.35= -2a
Multiply both sides by 5
12.5b-6.75= -10a
Multiply both sides by -1
-12.5b+6.75=10a
Combine equations:
-12.5b+6.75= -5b+4.2
Add 12.5b to both sides
6.75=7.5b+4.2
Subtract 4.2 from both sides
2.55=7.5b
7.5b=2.55
Divide both sides by 7.5
b=0.34
A banana costs £0.34
If you would like to check and see if it is true, (I already checked, it is) you can use the formulas I gave at the start of the explanation.
10a+5b=4.2
8a+10b=5.4
a=0.25
b=0.34
