Final answer:
To estimate the thickness of the two boards, add their individual thicknesses. The equation that represents the estimated thickness is 9/8 inch.
Step-by-step explanation:
To find the approximate thickness of the two boards, you can add their individual thicknesses. One board is ⅝ inch thick, and the other board is ½ inch thick. To estimate their combined thickness, add these two values: ⅝ + ½. Convert the fractions to the same denominator: ⅝ becomes 5/8 and ½ becomes 4/8. Then add the fractions: 5/8 + 4/8 = 9/8.
To simplify the fraction, divide the numerator and denominator by their greatest common divisor, which is 1 in this case. 9/8 ÷ 1/1 = 9/8. So, the equation that represents the estimated thickness of the two boards is 9/8 inch.