First thing you have to do is look at the number 10 and number 15. which number goes into 10 and 15 , its 5. 5 goes outside the first bracket. = 5( )next you have to find the like terms, both 10pq and 15pqr both have pq in common. so you can take the pq outside the bracket too.5pq( ).what does 5pq have to be multiplied by to get 10pq? yes its 2 so 2 is the first number inside the bracket. 5pq has to be multiplied by 3r to get 15pqr.so the final answer is 5pq(2 + 3r)