Let
x ------> number of hours Job A
y -----> number of hours Job B
we have that
x+y=22 ------> x=22-y ------> equation 1
6.40x+6.60y=143.60 ------> equation 2
Solve the system of equations
substitute equation 1 in equation 2
6.40(22-y)+6.60y=143.60
solve for y
140.8-6.40y+6.60y=143.60
0.20y=143.60-140.8
0.20y=2.8
y=14 hours
so
x=22-14=8
therefore
number of hours Job A was 8
and
number of hours Job B was 14