5.2

1: See page 224.

12: Substitute 10x – 8 in for y.

16: Solve for x in the simpler equation, and then substitute the expression in for x in the other equation.

19: Write one equation to show that one variable is three times as much as the other, and write another equation to show that the total is 180.

21: Keep your equations very simple and easy to calculate values.

30: The equation of a vertical line is x ＝ a number, and the equation of a horizontal line is y ＝ a number.

33: This is the same as #19, except there is an equation for how much bigger one variable is than the other rather than an equation for the total.

34: The value of n nickels and d dimes is 5n + 10d.

39: Remember to subtract -3, not 3.

40: First distribute the 4 and the 3, then combine like terms.