Newton
a number plus six
x+6
a number minus a number
x-y
a number plus 4
x+4
3 plus a number
3+x
Ten altogether with a number
10+x
any number plus three
x+3
The addition of a number and 6
x+6
Sixteen added by twice a number
16+2x
a number reduced by six
x-6
Any number reduce twice the number
x-2x
five added with a number
5+x
Double a number minus eight
2x-8
Any number added by five
x+5
a number plus double the same number
x+2x
A number increased by triple the number
x+3x
6 added with a number
6+x
Marco's age plus Fran's age
x+y
Any number plus four
x+4
A number decreased by twice a number
x-2y
Twice a number decreased by seven plus the same number
2x-7+x
triple a number decreased by seven
3x-7
Seventeen decreased by triple a number
17-3x
Six times a number plus two minus the same number
6x+2-x
any number added plus triple another number
x+3y
The speed of something pus 15
x+15