Answer:
Y = 27.
Step-by-step explanation:
40 - 13 = 27. If we check our math 13 +27 does equal 40 making the equation correct.
Im not sure if you need to find the area or de expression of how to find the AREA. but what you do if explain how you can find it by multiplying that will be 4.. and then also 4? Im not sure but you can try
Let: x be Amy's marbles
3x be Robin's marbles
15+3x be Sam's marbles
x+3x+15+3x=99
7x+15=99
7x=99-15 (transfer 15 to the right side of the equation, then minus)
7x/7=84/7 (divide both sides of the equation by 7)
x=12
Now substitute:
x = 12 (Amy's)
3x = 3*12 = 36 (Robin's)
15+3x = 15+3*12 = 51 (Sam's)
12+36+51 = 99
Therefore, Amy has 12 marbles, Robin has 36 marbles and Sam has 51 marbles.