a) the price of the pencil and the price of the pen are both unknown variables in this equation. This means that you can make the pencil = x and the pen = y. The pencil is 25 cents more than the pen, so y (the pen) + 25 cents = x (the pencil). Hence, x = y + 25.
b) Using the same logic as the last question, let’s make Bob = x and Mary = y. Bob’s age is six years less than Mary’s age, so we can express this as x (Bob’s age) = y (Mary’s age) -6, so your final answer is x = y - 6.
c) i) let the original number be x and the next odd number be y. Every other number is an odd number, so you can express this problem as y = x + 2.
ii) Using the logic from the last question, the odd number before x would be x - 2, so the expression would be y = x- 2
Hope this helped :)
