You can put this solution on YOUR website! 3 * 50 = 150 so the 3 prime number will have to be something close to but less than that.
here's a list of possible candidates.
31 37 41 43 47 53 59 61 67 71
it looks like 43 and 47 and 53 would be the prime numbers that add up to 143.
43 + 47 = 90 and 90 + 53 = 143 - they're the ones.