Answer:
Step-by-step explanation:
Let C represent the number of hours that Carlito worked.
Let J represent the number of hours that Juan worked.
Let S represent the number of hours that Sara worked.
1) The equation that would represent the fact that altogether they worked 80 hours is
C + J + S = 80
2) The equation that would represent the fact that Juan worked 5 more hours than Carlito is
J = C + 5
3) Sara worked 3 times as many hours as Juan. It means that
S = 3J
Substituting J = C + 5 into S = 3J, it becomes
S = 3(C + 5)
S = 3C + 15
Substituting S = 3C + 15 and
J = C + 5 into C + J + S = 80, it becomes
C + C + 5 + 3C + 15 = 80
C + C + 3C + 5 + 15 = 80
5C + 20 = 80
5C = 80 - 20
5C = 60
C = 60/5
C = 12
S = 3C + 15 = 3 × 12 + 15
S = 51 hours
Sara worked for 51 hours