Can someone ? im confused on what to do on it

Prove that the value of the expression 7^8–7^7+7^6 is divisible by 43.

Arectangle has a width of 5 cm and a length of 10 cm. if the width is increased by 3, how does the perimeter change?

Solve the problem by using a venn diagram a group of students were surveyed about their taste in music. they were asked how they like three types of music: rock, country western and jazz. the results are summarized below: no one dislikes all three types of music. six like all three types of music. eleven don’t like country western. sixteen like jazz. three like country western and jazz, but not rock. six don’t like rock. eight like rock and country western. seven don’t like jazz. how many students were surveyed?