9(5x+13)=252
45x+117=252
45X=252-117
45X=135
X=3
1) 25.5 / 5 x 3 = 15.3 за три дня
2) 15.3 / 3 = 5.1 км
<span>f (x) = 2,1х-7,5
</span>f (0) = 2,1*0-7,5 = -7,5
f (3) = 2,1*3-7,5 = -1,2
<span>f (4) = 2,1*4-7,5 = </span>0,9
<span>f(х) = 0,5х+2
</span><span>f(0) = 0,5*0+2 = 2</span>
<span>f(3) = 0,5*3+2 = 3,5</span><span>
f(4) = 0,5*4+2 = 4</span>