Phil would have 36 rocks.
Method:
(First you read the question carefully and write down what you see)
3x + x = 48
(Add all like terms on the left if so)
4x = 48
(Divide the number of variables on both side)
x = 12
(Last, plug in the x value)
Peter have 12 rocks, and 12 times 3 will give you 36, the number of phil rocks. Add them up and you will get 36 rocks in total
3(12) + 12 = 36
Hope this helps!!
