Sheila has 5 times.
Dave has 1 time.
Together they have (5 + 1) = 6 times.
6 times = 18
Divide each side by 6 : 1 time = 3
Sheila has 5 times = (5 x 3) = 15 markers.
Dave has 1 time = 3 markers.
Total = (Sheila + Dave) = (15 + 3) = 18 markers.
Check, check , and double check.