Question

7+{7+7x[7+7x(a+7:7)]}=455

Answer 1

7+{7+7×[7+7×(a+1)]}=455

7+7×[7+7×(a+1)]=448

7×[7+7×(a+1)]=441

7+7×(a+1)=63

7×(a+1)=56

a+1=8

a=7

Answer 2

7 + { 7 + 7 × [ 7 + 7 × ( a + 7 : 7 ) ] } = 455

7 + { 7 + 7 × [ 7 + 7 × ( a + 1 ) ] } = 455

7 + 7 × [ 7 + 7 × ( a + 1 ) ] = 455 - 7

7 + 7 × [ 7 + 7 × ( a + 1 ) ] = 448

7 × [ 7 + 7 × ( a + 1 ) ] = 448 - 7

7 × [ 7 + 7 × ( a + 1 ) ] = 441

7 + 7 × ( a + 1 ) = 441 : 7

7 + 7 × ( a + 1 ) = 63

7 × ( a + 1 ) = 63 - 7

7 × ( a + 1 ) = 56

a + 1 = 56 : 7

a + 1 = 8

a = 8 - 1

a = 7