If a=4, b=5, and 2 (ab + bc + ca) = 202, find the value of c

c = 9

Step-by-step explanation:

First we need to substitute in our known values:

2 ((4X5) + 5c + 4c) = 202

Next we can do the inner multiplication and combine our like terms:

2 (20 + 9c) = 202

Now we distribute the 2:

40 + 18c = 202

Subtract 40 from both sides:

18c = 162

Lastly, divide both sides by 18 to get:

c = 9

Check our work:

2 ((4X5) + (5X9) + (9X4)) = 202

2 (20 + 45 + 36) = 202

2 (101) = 202

202 = 202

in this equation c = 9