We'll call the unknown number "n."
Three more than (8 times a number) is equal to 19
3 more than (8 times a number) = 19
3 + (8 times a number) = 19
3 + (8 * n) = 19
Now, we solve:
3 + 8n = 19
3 + 8n - 3 = 19 - 3
8n = 16
8n /8 = 16 /8
n = 2
Hope this helps! :)