Parking lot has 121 spots. Ratio of senior to junior is 7 to 4. How many spots go to each grade level?

I am going to build a chart this is best when using ratios

seniors junior total

7 4

*? * ? * ?

Totals 121

The way we fill out this chart is that we add the rows and multiply the columns.

So we add 7 + 4 and fill it in our chart we get 11

seniors junior total

7 4 11

*? * ? * ?

Totals 121

now to find the * ? need to divide 121/11 to get * ?

121/11 = 11

so now our chart looks like this

seniors junior total

7 4 11

11 11 11

Totals 121

Now we multiply each column

so

7 * 11 = 77

4*11 = 44

now our chart look like this

seniors junior total

7 4 11

11 11 11

Totals 77 44 121

so seniors get 77 spaces

and juniors get 44 spaces.