HELP我做一些mathematics

1) 2 subtracted from 4 times a certain number is 10. Find this number.
let the number be x
4x-2=10
4x=12
x=3
so the number is 3

2) The sum of three consecutive even numbers is 102, find these three numbers.
let the three numbers be x,(x+2),(x+4)
x+(x+2)+(x+4)=102
3x+6=102
3x=96
x=32
so the three numbers are 32,34 and 36

3) Alice had some $10 banknotes, $20 banknotes and $100 banknotes. The number of $10 baknotes is 3 times that of $20 banknotes. The number of $20 banknotes is 8 times that of $100 banknotes. If Alice had $1500, find the number of $100 banknotes she had.
let x be the number of $100 banknotes she had.
then 8x is the number of $20 banknotes she had.
24x is the number of $10 banknotes she had.
100x+20(8x)+10(24x)=1500
100x+160x+240x=1500
500x=1500
x=3

so she had 3 $100 banknotes

2.) let the first number is y , the second number is (y+2) , the third is (y+4) .
y+(y+2)+(y+4)=102
3y+6=102
3y=96
y=32
so , the first number is 32 , the second number is 32+2=34 and the third is 32+4=36.

可惜,我英文不好,否则我会帮你做.