How do i solve 2 and 3.(6th grade math)

Look at arnold's attempt to solve the equation for b: 3b = 12 b = 3 · 12 b = 36 describe the mistake that arnold made.

Which of the following could be the ratio of the length of the longer leg 30-60-90 triangle to the length of its hypotenuse? check all that apply. a. 313 6 b. 3: 215 c. 18: 13 d. 1: 13 e. 13: 2 of. 3: 15

The measures of the legs of a right triangle are 15m and 20m . what is the length of the hypotenuse