R is partly constant and partly varies with E when R=290 E=200 and when R=140 E =800 find the formula which connect R and E find R when E =55
R = mE + b
for the given:
290 = 200m +b
140 = 800m + b
subtract them:
-150 = 600m
m = -150/600 = -1/4
in 290 = 200m + b
290 = 200(-1/4) + b
340 = b
R = (-1/4)E + 340
sub in E = 55 to find R