Hello! I have two math questions:

Question

1.) Marcos has 28 coins that are all nickels (n) and dimes (d). The value of the coins is $2.05. Which system of equations can be used to find the number of nickels and the number the dimes?

A. n + d = 28
5n + 10d = 205


B. n + d = 28
10n + 5d = 2.05


C. n + d = 205
n + d = 28


D. 10n + 5d = 205
n + d = 28

2.) Two groups of students order burritos and tacos at a local restaurant. One order of 3 burritos and 4 tacos costs $11.33. The other order of 9 burritos and 5 tacos costs $23.56. Which system of equations represents this problem situation?



A. x + y = 7
x + y = 14


B. 3x + 4y = 11.33
9x + 5y = 23.56


C. 3x + 4y = 23.56
9x + 5y = 11.33


D. x + y = 12
x + y = 9

Answer 1

#1 should be obvious
since d is "dime", it has to be multiplied by 10 (10 cents in a dime)
and n is "nickels" it has to be multiplied by 5
So what do you think?

#2, Once you define what x and y represent, the answer should be obvious as well.
I would have used b and t instead of x and y.

Answer 2

So
#1 is A and #2 is D?

Answer 3

correct for #1, wrong for #2

#2
If x is cost of buritos, y is cost of tacos
"3 burritos and 4 tacos costs $11.33" --->3x+4y = 11.33

"9 burritos and 5 tacos costs $23.56" ----> 9x + 5y = 23.56

B !!!!

Now , how easy was that? Notice how I just translated the "math" into English ?