The constant of proportionality is the ratio between two directly proportional quantities. Two quantities are directly proportional when they increase and decrease at the same rate.
The constant of proportionality k is given by k=y/x where y and x are two quantities that are directly proportional to each other. Once you know the constant of proportionality you can find an equation representing the directly proportional relationship between x and y, namely y=kx, with your specific k.
You would convert the 4 feet into inches which would be 48in. You would add the 9in and the 19.5in and come up with 76.5in. Then you just convert the 76.5in to 6.375ft
The answer is a) 35 because if you set 21/49 and 15/h equal to eachother and cross multiply it should lead you to 21(h) = 15(49) which then equals 21h = 735 and if you divide 21 on both sides you should get h = 35
