Answer:
57
Step-by-step explanation:
3^r = 19
Multiply each side by 3
3 * 3^r = 19 *3
We know that a^b * a^ c = a^ ( b+c)
3^1 * 3^r = 19 *3
3^(r+1) = 19*3
3^(r+1) = 57
