int temp=40; // variable for temperature
int redLED=10; // variable for LED

void setup() {
  // put your setup code here, to run once:
pinMode(10, OUTPUT); // pin 10 configured as an output pin
}

void loop() {
  // if the temperature is larger then 35 on the LED:
if(temp>35)
{
  digitalWrite(redLED, HIGH);
}
}