7 plus the quantity of 9 increased by a number
The phrase a number means an arbitrary variable, let's call it x:
x
9 increased by a number means we add 9 to x
9 + x
7 plus this quantity means we add (9 + x) to 7
7 + (9 + x)
The phrase a number means an arbitrary variable, let's call it x:
x
9 increased by a number means we add 9 to x
9 + x
7 plus this quantity means we add (9 + x) to 7
7 + (9 + x)