Nina thinks of a number.she subtract 2.5 then doubles her answer .she adds 7 and then halve her answer . The number is left with 15. What was her starting number

Question

Help me please and show how to work it out .please answer as soon as possible. Thank you

Answer 1

Let n represent the number.

n-2.5 subtract 2.5

2(n-2.5) double the answer

2(n-2.5)+7 add 7

(2(n-2.5)+7)/2 halve the answer

(2(n-2.5)+7)/2=15 make equation.

Solve the equation:

Double both sides: 2(n-2.5)+7=30

Subtract 7 from each side: 2(n-2.5)=23

Halve each side: n-2.5=11.5

Add 2.5 to each side: n=14, the number was 14.

There’s another method you can use which you might find easier: the Undo Method:

Read your word problem backwards, reversing the instructions.

Halve the answer becomes double the answer. The answer was 15, so double it=30.

Adds 7 becomes subtracts 7=23.

Doubles her answer becomes halves her answer=11.5.

Subtract 2.5 becomes add 2.5=14, the number you started with!