Question 466523
Let B = Bob's present age and J = his daughter Jane's present age.
1) {{{B = 5J}}} "Bob is 5 times the age of his daughter Jane."
2) {{{B+5 = 3(J+5)}}} "In 5 year's time, Bob will be 3 times Jane's age."
Into equation 2), substitute {{{B = 5J}}} from equation 1) and solve for J.
3) {{{(5J)+5 = 3(J+5)}}} Simplify this.
4) {{{5J+5 = 3J+15}}} Subtract 3J from both sides.
5) {{{2J+5 = 15}}} Subtract 5 from both sides.
6) {{{2J = 10}}} Divide both sides by 2
7) {{{highlight(J = 5)}}} Now substitute this value of J into equation 1) to find the value of B.
8) {{{B = 5(5)}}}
9) {{{highlight_green(B = 25)}}}
Bob's present age is 25 and his daughter Jane's present age is 5.