A knife is three times the cost of a spoon
9 spoons and 12 knives cost £82.80
Work out the cost of 1 knife

Select true or false to tell whether the following conditional p q is true or false. use the truth table if needed. if a week has seven days, then a year has twenty months.

On a string instrument, the length of a string varies inversely as the frequency of its vibrations. an 11-inch string has a frequency of 400 cylces per second. find the frequency of a 10-icnch string.

How do i start to solve? would appreciate a walk-thru! a bird sitting 16ft above the ground in an apple tree dislodges an apple. after how many seconds does the apple land on the ground? (assuming that no branches will interfere with it's fall)