Let x rep. numbers of boys that can work at \(\frac{5}{4}\) the rate at which the 10 girls work For 1 hrs, x boys will work for \(\frac{\frac{1}{5} \times 10}{4}\) x = \(\frac{5}{4}\) x 10 = 8 boys 8 boys will do the work of ten girls at the same rate 4 + 8 = 12 bous cut the field in 5 hrs for 3 hrs, \(\frac{12 \times 5}{3}\) boys will be needed = 20 boys.