Twice a number is decreased by 7, and this quantity is multiplied by 3. the result is 9 less than 10 times the number. What is the number?

(7-2x) 3 = 9-10x

x = - 3

Step-by-step explanation:

we let the number to be x.

twice a number=2x is decreased by 7 that is to say 7-2x, is multiplied by 3, we have (7-2x) 3.

the result is 9 less than 10times the number which is = 9-10x.

so bringing all these together we have;

(7-2x) 3=9-10x.

what is the number?

solving, we have:

(7-2x) 3=9-10x

21-6x=9-10x

21-9 = - 10x+6x

12 = - 4x

dividing both sides by - 4 we have our number

x = - 3.

for proof we can substitute x=-3 into the equation.

21-6 (-3) = 9-10 (-3)

21+18=9+30

39=39