Answer:
40 sandwiches
Explanation:
egg sandwiches : tuna sandwiches
2 : 3
Multiply by x because we do not know how many sandwiches, just the ratio
2x : 3x
Add 15 tuna sandwiches
2x : 3x+15
Now the ratio is 1:3
egg sandwiches : tuna sandwiches
1 : 3
Multiply by y because we do not know how many sandwiches, just the ratio
y : 3y
Set the number of egg sandwiches equal
2x =y
then set the number of tuna sandwiches equal
3x+15 = 3y
We know have a system of 2 equations and 2 unknowns
Substitute y =2x into the second equation
3x+15 = 3(2x)
Distribute
3x+15 = 6x
Subtract 3x from each side
3x-3x+15 = 6x-3x
15 =3x
Divide by 3
15/3 = 3x/3
5 =x
egg sandwiches : tuna sandwiches
2 : 3
Multiply by x because we do not know how many sandwiches, just the ratio
2x : 3x
2*5 3*5
10 15
He originally made 10 egg sandwiches and 15 tuna sandwiches
Then he made 15 more tuna sandwiches
The total number of sandwiches he made is
10+15+15 = 40 sandwiches