4. A concert hall has its seats arranged so that each row has thirty more seats than the row in front of it. a) If the hall has 20 rows and the third row has 120 seats how many seats are in the last row?

b) How many seats are there altogether?

Please help me. I can't figure out how to solve this properly.​

the answer is d

hope this

you are playing an adventure game on your computer. you come across a troll who won't let you pass and there is no other way to get to the other side of the river except over the bridge he is guarding.

the troll is a nerd. he takes great delight in watching people struggle with his problems. very few get them. he only gives you one chance and then he changes the puzzle. you have to solve this one.

before you are four blocks. they are numbered 11,6, -7,21.

he tells that the answer he wants is minus and between -1 and - 2. you can use +, -, ×, ÷   ( and ) as many times as you like or no times at all. you don't like the way he's looking at you, but you need to cross the bridge. what do you do?

answer: 1 box of pens at the store ? ? pens in the box