parents = mothers + fathers, 3/4 * m and 9/10 * f held full-time jobs, if m = .4 * parents = .4 * (m + p), then what percent of the parents did not hld full-time jobs? since we want to know what percent of parents did not hold full-time jobs, and we know that 3/4 * m and 9/10 * f held full-time jobs, then we know that 1/4 * m and 1/10 * f did not hold full-time jobs, since m = 40% of the parents = .4 * ( mothers + fathers) = .4m + .4 f => m = .4m + .4f => .6m = .4f => f = 3/2 m = 3/2 * .4 parents = .6*parents, thus, the answer is: 1/4 * .4 + 1/10 * .6 = .1 + .06 = .16 = 16% | 
