What’s the error? and how do you correct it?

The mistake is that they switched the value of b with c. They said that c=8, when we actually don't know the value of c. They should have had a second step that looks like this: 6^2+8^2=c^2

You fix this mistake by correcting the values of b and c: 6^2+8^2=c^2

Hope this helps :)

236 cm 16 time 12 = 192

6 times 7 = 42

192+42