Follow the steps for 8
(1) 8 * 2 = 16
(2) 16 * 5 = 80
Note: you could just combine the first 2 steps and multiply by 10 to start with. Much easier: just add a 0 onto 8.
(3a) 12 * 8 = 96
(3b) 96 - 24 = 72
(3c) So you want to take 1/2 72 which is 36
(4) 36 + 80 = 116
Let's try this with x.
(2) x * 10 = 10x
(3) 1/2 (12*x - 24)
(3) 10x + 1/2 (12x - 24)
(3) 10x + 6x - 12
(4) 16x - 12
Problem B
Math wiz would add 12 to the number given to her and then divide by 16. That's pretty complicated to do quickly.
For example Let the original number be 1221
(2) Multiply by 10 12210
(3) Take 1/2 the difference between 12 times 1221 and 24 which is 1/2(14652 - 24) = 7314
And add this result to 12210
7314 + 12210 = 19524
Tell her the number. She has to add 12
19524 + 12 = 19536 And divide by 16
to get 1221.
Pretty complex even for a wizard.
The answer is X>50. Hope this helps!
3(3b+2)=-30 perform indicated multiplication on left side...
9b+6=-30 subtract 6 from both sides
9b=-36 divide both sides by 9
b=-4
