The proportion reads:
210/n = 300/440
we need to solve for "n"which is in the denominator, so we first "cross multiply"as shown below:
210 * 440 = 300 * n
operate on the left:
92400 = 300 * n
and now divide both sides by 300 in order to isolate "n"
92400/300 = n
therefore n = 308
