How do I solve (-4.25+8)-3.5 ?

The hawaiian alphabet has 12 letters. how many permutations are posible for each number of letters?

Expresa commuter train leaves downtown sation and travels at a average speed of 55 miles per hour towards the north side sation, which is 50miles away. thirty minutes later, express commuter train #7 leaves north side and travels at a average speed of 35miles per hour towards downtown sation. at the moment the two trains pass each other, how far(in miles) is train #12 from the downtown sation and how long(in minutes) has the #12 train been traveling

Which sums are equal to 1hold 6/8? choose all answers that are correcta.1/8+6/8b.12/8+2/8c.8/8+1/8 +1/8+1/8+1/8+1/8+1/8d.8/8+6/8