The table shows data gathered by an environmental agency about the decreasing depth of a lake during the first few months of a drought.

time (weeks)

lake depth (feet)

0 346.0
2 344.8
5 343.0
7 341.8
10 340.0
12 338.8
the lake's depth after four weeks will be

(0,346)(2,344.8)
slope = (344.8 - 346) / (2 - 0) = -1.2 / 2 = -0.6

y = mx + b
slope(m) = -0.6
use either of ur points (0,346)...x = 0 and y = 346
now we sub and find b, the y int
346 = -0.6(0) + b
346 = b

so ur equation is : y = -0.6x + 346

after 4 weeksx = 4
y = -0.6(4) + 346
y = -2.4 + 346
y = 343.6 <=== after 4 weeks it will be 343.6 

Basic algebra equation. first set up your equation: divide out 9.and now you are left with 2x + 4 = 8.