Just 12 it is algebra
a) Lets call the elevation e 1536 = 45 + 7e b) 1536 = 45 + 7e subtract 45 from both sides 1491 = 7e divide by 7 231 = e done!
Let's say that the variable for Lake Athabasca will be "a". Your equation is 1536 (Lake Louise's elevation) = 7a (7 times the elevation of Lake Athabasca) + 45 (45 m higher, which is added to the 7a). 1536= 7a + 45 Subtract 45 from both sides to get the coefficient and the variable on one side. 1491=7a Divide both sides by 7 to get the variable alone. 1491/7=7a/7 213=a The elevation of Lake Athabasca is 213 meters.