Aleks's team uses 5 times as many white volleyball as tan volleyballs for practice.
⇒ W = 5 × T (i)
also it is given His team uses 7 tan volleyballs.
⇒ T = 7 ⇒ putting in equation (i)
W = 5 × 7
⇒ W = 35
So Aleks's team uses 35 white volleyballs for practice.