All parallelograms are

Which letters from the table represent like terms? a and b b and c a and d b and d

What percent of 18 is 24? and plz explain thx.

Which of the following would be a reasonable estimate for the weight of a pencil? a. 1 × 10^-20 lb b. 1 × 10^20 lb c. 1 × 10^2 lb d. 1 × 10^-2 lb