Ameal of a chicken sandwich and some pasta salad had 150 grams of carbohydrates. the pasta salad had 30 grams more than twice the grams of carbohydrates in the chicken sandwich. find the number of grams of carbohydrates for both.

Ok so use what you know

the pasta and the chicken come up to 150grams
so... P+C=150

we also know that the pasta is 30 more (added) than twice(multiplying) the grams as the chicken.
P= 30+ 2C

so we have to take that and substitute into our first problem so that it looks like this.

(30+ 2C)+C=150
30+3C=150

now we're going to find  the grams of "C"

30+ 3C= 150
3C=120
C=40 gram

so the chicken has only 40 grams 
we know that together the pasta and chicken came to 150 gram so by doing some simple subtraction we see that the pasta had 110 grams