Дана система уравнений: {6a+b=70a−b=0
Вычисли значение переменной a. ДАЮ 38 БАЛЛОВ

Помогите пожалуйста!!! 

fill in with past simple or past continuous:

Last night I was (be) alone at home. I 2)____(lie) on my bed and I 3)____ (watch) TV when 14)     _____ (hear) a strange noise. The noise 5) _____ (come) from the kitchen. I 6)____ (go) downstairs, 7)____ (pick up) a heavy vase from the table and 8)_____(head for) the kitchen. 19)  ____ (open) the door very slowly. Then I 10) _____ (see) someone. He

11)____ (search) in the fridge. I 12) ____(be) so frightened that  I 13) ____(drop) the vase I 14)____ (carry) and it 15) ____ (crash) onto the floor. The man ___ (turn) towards the door and I 17) ____(see) his face. It was my husband!