Find the missing number in this proportion 10/15=?/21

In djkl, side jk measures 10.6 inches, side kl measures 7 inches, and side jl measures 5 inches. based on the information that is provided, which could be a correct set of angle measures for these sides? angle j = 23.2°, angle k = 33.5°, angle l = 23.2° angle j = 23.2°, angle k = 33.5°, angle l = 123.2° angle j = 123.2°, angle k = 23.2°, angle l = 33.5° angle j = 33.5°, angle k = 23.2°, angle l = 123.2°

What is the measure of ac? 5 units 13 units 26 units 39 units

The triangles are similar. what is the value of x? show your work.