Which set of numbers forms a right triangle? 2.1, 4, 7
8, 10, 12
8, 15, 17
3.4, 4.5, 5.3

Scale factor of 2 is used to enlarge a figure as shown below the area of is 18 in.²

Offering 30 if a plus b plus c equals 68 and ab plus bc plus ca equals 1121, where a, b, and c are all prime numbers, find the value of abc. the answer is 1978 but i need an explanation on how to get that.

Money off coupons have been circulated to 300 households. only 2/5 of these were redeemed (used) in the local supermarket to get a free shampoo. what fraction of coupons were unused? (ps: write how you got the answer)