The Sum of two numbers is 9 and their diffrence is 7, What are the two numbers?

the two numbers are 8 and 1

Step-by-step explanation:

Let the two numbers be represented by x and y.

We derive the equations to solve the problem.

X + y = 9equation 1

X-y =7equation 2

Add the two equations to eliminate y

2x = 16

Divide both sides by 2

x = 16/2 = 8

If x = 8, substitute the value of x into equation 2 to get the value of y

8 - y = 7

make y the subject

8 -7 = y

1 = y

y = 1

x=8,y=1

Step-by-step explanation:

Let the two unknown be x and y

Sum of the two unknown is 9

That is

x+y=9...(1)

Difference between the two unknown is 7

x-y=7(2)

Add (1) and (2)

2x=16

Let's make x the subject of formula

x=8

Let's substitute the value of x into (2)

8-y=7

Make y the subject of formula

y=8-7

y=1

Therefore x=8,y=1

This didn't really state what you wanted to find. But I'm assuming you're trying to find how much of the 60 cans she sold if you collected 81%. 
In this case your equation would be 81% of 60. 
The first thing you do is convert 81% to a decimal by moving the decimal place 2 spaces to the left. So you get .81 of 60
"of" states multiplication, so .81 times 60 is 48.6
So Maggie collected 48.6 cans out of 60