i got this question i know how he got everything else expect the 13

2x^2+10x+3x-15=100 form this he got=====> 2x^2+13x-115=0

i know how he got everything else expect for the 13

i got 2x^2+7x-115=0

how i got this==> i move over the 100 making it -100 and then i combine the -15 with the -100 and i got==> -115

and then i minus -3 from 3x and 10==> the 3 and -3 cancel out

so i got====> 7x by taking away 3 from 10x

did he just add the 10x and 13x????