Let workout Plan A last a hours, and Plan B last b hours.
we are assuming personal training for each client.
i)
"On Monday there were 2 clients who did Plan A and 3 who did Plan"
the total time spent is : 2*a + 3*b =2a+3b
ii)
"On Tuesday there were 4 clients who did Plan A and 8 who did Plan B"
the total time spent was 4*a+8*b=4a+8b
iii) "Joe trained his Monday clients for a total of 7 hours"
so 2a+3b = 7
iv)
"Joe trained his Tuesday clients for a total of 17 hours"
so 4a+8b=17
v) thus we have the following system of equations:
2a+3b = 7
4a+8b=17
multiply the first equation by -2, and then add both equations, to eliminate a:
-4a-6b=-14
4a+8b=17
-------------------
2b=3, so b=3/2
2a+3b = 7
2a+3(3/2)=7
2a+9/2=7
multiply by 2:
4a+9=14
4a=5
a=5/4
Answer :
Plan A lasts 5/4=1.25 h
Plan B lasts 3/2=1.5 h
