let
x---------> Aviva’s age
y--------->Kanti’s age
z--------> Lakshmi’s age
we know that
y=x-3-----> equation 1
z=2*y-----> equation 2
substitute equation 1 in equation 2
z=2*(x-3)
so
Aviva’s age------> x
Kanti’s age-------> x-3
Lakshmi’s age----> 2*(x-3)
therefore
the answer is the option
b) 2(x-3)
Answer:
infinitely many solutions
Step-by-step explanation:
I assume that you meant
3x = -12y + 15 and x + 4y =5 (you accidentally omitted the 'y')
Multiplying the second equation by 3 yields
3x + 12y = 15
... which is identical to the first equation. Thus, the two lines coincide, and we conclude that there are infinitely many solutions.
1) it costs

so is D
2) the amount of the discount is -30%

so is A
3) -0.3

so is B
4) Chad paid 0.7

so is C