Answer:
Adult=58
Step-by-step explanation:
c=child, a=adult
6.4c+9.7a=1145 equation 1
c+a=149 equation 2
a=149-c modified equation 2 to isolate a
6.4c+9.7(149-c)=1145 substitute value of a from equation 1 into equation 2
6.4c+1445.3-9.7c=1145
-3.3c=-300.3
c=91
solve for a
c+a=149
91+a=149
a=58
Check answer:
6.4c+9.7a=1145
6.4(91)+9.7(58)=1145
582.40+562.60=1145
1145=1145
A + B + C = 518 ft^3
A = 1/3B, or 3A = B
B = C
A + B + C = 518 ft^3
1/3B + B + B = 518
7/3B = 518
B = 518×3/7 = 222 ft^3
A = 1/3B = 1/3×222 = 74 ft^3
C = B = 222 ft^3
