1.3 meter
Step-by-step explanation
Step 1
Let
red dot = teacher
green dots= students
space between the teacher and the first student is 1.5=black line
space between the teacher and the last students is 6.7 m= blue line
space between each estudent= unknow value= purple line= x
Step 2
make the equation
blue line = blackline + 4*purple line
replace,

Step 3
solve for x

Rounded it is 1.3 meter