May I see the statements ????
In this type of calculations, we decompose 13 by checking the lowest powers of the base, that is 40. for example we check 40^2, or 40^3 and compare it to 85
Notice
40*40*40=64,000
so we check how many time does 85 fit into 64,000:
64,000/85=752.94
85*753=64,005; 64000-64,005=-5
this means that

thus

Answer: 10 (mod85)
Remark, the set of all solutions is:
{......-75, 10, 95, .....}, that is 85k +10
Answer: r = 11
Step-by-step explanation:
We know that the point (-2, r) lies on the graph of:
2*x + y = 7.
Then, if we that point is on the graph of the equation, we can replace the values and we will have:
2*(-2) + r = 7
and now we solve this for r-
-4 + r = 7
r = 7 + 4 = 11
r = 11
You can set this up as 5(3+4)....then, distribute by multiplying the terms in parentheses by 5. This gives you 15+20, which equals 35.
The answer is 5/15 which is simplified to 1/3