The left and right page numbers of an open book are two consecutive intergers whose sum is 199 find these page numbers

Let's make an equation.

x+y=199

Let's have x be the larger number. Since they are consecutive, they are one away. Let's make an equation for x.

y+1=x; Let's plug this into the first equation.

(y+1) + y=199

2y+1=199; subtract one.

2y=198

Divide.

198:2=99

So, the smaller number is 99, so the bigger number is 100. You could also tell that 199 can be split into 100 and 99, which are consecutive numbers.