1.
a)
[tex]k+9 = 99 \ \ |-9\\\\\boxed{k = 90}[/tex]
b)
[tex]\frac{k+2k-6+3k+3}{3} = 15\\\\\frac{6k-3}{3} = 15\\\\2k-1 = 15 \ \ |+1\\\\2k = 16 \ \ /:2\\\\\boxed{k = 8}[/tex]
2.
a)
[tex]d + 4d+1 = 11 \ \ |-1\\\\5d = 10 \ \ /:5\\\\\boxed{d = 2}\\\\\boxed{4d = 4\cdot2 = 8}[/tex]
b)
[tex]3x-2+3x-2 + x+1+1+x+2x = 18\\\\10x-2 = 18 \ \ |+2\\\\10x = 20 \ \ /:10\\\\\boxed{x = 2}\\\\a = b=3x-2 = 3\cdot2-2 = 6-2 = 4\\\\c=d=x+1 =2+1 = 3\\\\e = 2x = 2\cdot2 = 4[/tex]
