Let us start by putting the value of x. When x=1, 7x−1+11x−1=1+1=2 When x=2, 7x−1+11x−1=7+11=17 When x=3, 7x−1+11x−1=49+121=170 When x=4, 7x−1+11x−1=243+1331=1574 As we can see 7x−1+11x−1 is an increasing function and the only value that satisfies 7x−1+11x−1=170,is x=3 Thus, the given equation has only 1 solution. Hence, option B is the correct answer.