2/5 plus 3/4 equals what?

14 pointslet x be the seats in the small van and y the seats in the large van. how many seats does the large van have? a company uses two vans to transport worker from a free parking lot to the workplace between 7: 00 and 9: 00a.m. one van has 9 more seats than the other. the smaller van makes two trips every morning while the larger one makes only one trip. the two vans can transport 69 people, maximum.how many seats does the larger van have?

How do you solve a question like this?

The square pyramid has a volume of 441 cubic inches. what is the value of x? 1/7x is the height x is the base