Answer:
a=2.48
c=9.52
Step-by-step explanation:
a+c=12
4a+7.5c=72.5 Given
a+c=12
-4a-7.5c=-72.5 multiply the equation by negative 1
-3a-6.5c=-60.5 simplify
-3a=-60.5+6.5c add 6.5c to both sides
a=-20.17+2.17c divide it by 3
now you would take that equation and plug it into an equation you already have since you have something to plug in for a, the easiest one to do is a+c=12
(-20.17+2.17c)+c=12 plug in the equation
-20.17+3.17c=12 simplify by solving for c
3.17c=30.17 add 20.17 to both sides
c=9.52 divide both sides by 3.17
now since you have found c, you can plug it in to you equation to solve for a now (use the ones from the second step). I am using the equation a+c=12.
a+9.52=12 plug in the variable and solve for a
a=2.48 subtract 9.52 to both sides
a=2.48
c=9.52
You substitute the y from the second eqaution to the y in the first equation
Answer:

Step by step explanation:

The question is probably incomplete. What i am assuming is that the person might ask for the previous ratio or the total number of pens and pencil in the drawer.
So if it is the previous ratio it obviously would be 47 - 5 : 17 -3 so 42 : 14 and in case he or she is asking for the total number of pens and pencils in the drawer before so they were 42 + 14 hence 56.
Answer:
Step-by-step explanation:
Any equation, for example 2r =2/3